One known type of fuse striker is of the spring actuated type wherein a striker pin is seated on a compressed spring that is held in compressed condition by a high resistance strain wire which upon interruption of the fuse is quickly melted due to the fact that shunt current through the high resistance strain wire causes melting and a resulting release of the pin which protrudes through the end of the fuse to provide an indication of the operated condition of the fuse or to actuate a signal or switching device.
Objections to the spring actuated type of striker assembly are due to the high cost and large physical dimensions thereof.
Another known fuse striker is of the so-called pyrotechnic or powder-actuated type wherein a powder charge is ignited by an ignition element to actuate piston means and thus to drive the striker pin into its operated condition.
The disadvantages of the powder actuated device center primarily around the fact that such mechanisms must be constructed of low tolerances so as to prevent the escape of piston actuating gases. Such constructions are particularly costly and are vulnerable to rough handling since the ignition element is usually of a high resistance fragile wire which is easily damaged because of its brittle nature.